第四纪年龄测定的新技术──热电高质谱铀系法的发展近况

近10年来国际上用热电离质谱代替α谱仪测定不平衡铀系样品的年龄，在造礁珊瑚、洞穴堆积物、年轻火山岩和湖泊沉积物等领域已取得了显著的成果。该技术有明显的优点，如样品用量少，测试时间短，测量精度高，测年范围宽，是中更新世至全新世以来有效的测年方法之一，可为全球变化研究提供高精度和高灵敏度的年龄谱，展示了热电离质谱技术如同加速器质谱技术一样，有广阔的应用前景。我们曾用MAT－262质谱仪对国内石笋标样（GBW04412，GBW04413）和国际珊瑚标样（RKM－4）进行过测试，取得了与标准值一致的结果。     

第四纪年龄测定的新技术──热电高质谱铀系法的发展近况

近10年来国际上用热电离质谱代替α谱仪测定不平衡铀系样品的年龄,在造礁珊瑚、洞穴堆积物、年轻火山岩和湖泊沉积物等领域已取得了显著的成果。该技术有明显的优点,如样品用量少,测试时间短,测量精度高,测年范围宽,是中更新世至全新世以来有效的测年方法之一,可为全球变化研究提供高精度和高灵敏度的年龄谱,展示了热电离质谱技术如同加速器质谱技术一样,有广阔的应用前景。我们曾用MAT－262质谱仪对国内石笋标样(GBW04412,GBW04413)和国际珊瑚标样(RKM－4)进行过测试,取得了与标准值一致的结果。     

热电离质谱法测定国际比对氧化铀芯块中的铀同位素比值

采用全蒸发-热电离质谱技术测量了国际比对二氧化铀样品中的铀同位素比值。比对结果表明,本实验室提交的²³⁴U/²³⁸U、²³⁵U/²³⁸U和²³⁶U/²³⁸U值与IAEA公布的参考值偏差分别为0.02%、-0. 003%和0. 97%,在实验室间分析测试能力评价中, Z (或ζ)分数分别是0.03(或0.05)、-0.05(或-0.07)和0.15(或0.25),均被评价为满意。     

Irregular structures observed below 71 km in the night-time polar D-region

A new rocket range, SvalRak, was opened in November 1997 at Ny-Ålesund (79°N) in the Svalbard archipelago. The first instrumented rocket was launched on 20 November, 1997, at 1730 UT during geomagnetically quiet conditions. The payload was instrumented to measure plasma parameters in the mesosphere and lower thermosphere, but the payload only reached an altitude of 71 km. This resulted in a very flat trajectory through the lower D-region. The positive ion concentrations were larger than expected, and some unexpected plasma irregularities were observed below 71 km. The irregularities were typically 100 m in spatial extent, with plasma densities a factor of two to five above the ambient background. In the dark polar night the plasma below 71 km must consist mainly of positive and negative ions and the only conceivable ionising radiation is a flux of energetic particles. Furthermore only relativistic electrons have the large energies and the small gyro radii required in order to explain the observed spatial structure. The source of these electrons is uncertain.     

GDK-1型自动测氡仪的研制和应用

简要介绍了采用电离法原理研制的一种静电计型检测氡气的测氡仪,达到了智能化的程度,并于1995年6月开始至1996年1月在北京太平庄自流井进行试验,后于2003年10月至今在该台站进行断层气的观测,并与SD-3型数字化测氡仪进行同步观测,从台站的试验结果可见,该仪器观测的数据稳定性较好,无需人工操作和没有人为操作引起的误差。     

雷暴云准静电场对夜间电离层D区的影响

模型，计算了雷暴云电荷突然对地放电后QE场大小 在0～90km高度上的分布. 对200C的正电荷对地放电后的计算表明，在放电1ms后，在65～78km的区域内，QE场大于大气的雪崩电场，而0.5s后，该电场迅速衰减到很低的水平. 在电 离层高度上，由于电子的热化时标和电离时标极短，在QE场的作用下，夜间局部低电离层会 有比较大的响应. 对Boltzmann方程数值求解的结果表明，在某些高度上，电子分布函数有 明显的高能尾巴；在63～83km的高度上，电子平均能量为3eV＜ε＜6eV；计算的电子数 密度 的峰值扰动表明，在65～78km的高度上，电子的数密度增加，最大的电离峰值约在74km处， 大约增加了3个数量级，比电磁脉冲（EMP）的电离效果大得多.     

热表面电离质谱法测定贫化铀样品痕量铀同位素比值及含量

选用磷酸为离子流发射剂,热表面电离质谱法分析纳克量级贫化铀样品的铀同位素比值,方法最大相对标准偏差2.9%。以233U为稀释剂,采用同位素稀释法对铀的含量进行测定,扩展不确定度为2.4%(K=2)。研究表明,在纳克量级的铀同位素比值测定中,来自铼带等铀本底的干扰影响不容忽视,需要进一步研究并扣除。     

The solubility of SO2 and the dissociation of H2SO3 in NaCl solutions

The pK ₁ ^* and pK ₂ ^* of H₂SO₃ have been determined in NaCl solutions as a function of ionic strength (0.1 to 6 m) and temperature (5 and 25 °C). The extrapolated values in water were found to be in good agreement with literature data. The experimental results have been used to determine the Pitzer interaction parameters for SO₂, HSO ₃ ^- and SO ₃ ^- in NaCl solutions. The resultant parameters for NaHSO₃ and Na₂SO₃ were found to be in reasonable agreement with the values for NaHSO₄ and Na₂SO₄. It, thus, seems reasonable to assume that the interactions of Mg²⁺ and Ca²⁺ with HSO ₃ ^- and SO ₃ ^- can be estimated from the values with HSO ₄ ^- and SO ₄ ^- until experimental values are available. Measurements of pK ₁ ^* and pK ₂ ^* in artificial seawater were found to be in good agreement with the calculated values using the derived Pitzer parameters. It is, thus, possible to make reasonable estimates of the activity coefficients of HSO ₃ ^- and SO ₃ ^- ions and pK ₁ ^* and pK ₂ ^* for the ionization of H₂SO₃ in marine aerosols.     

Oscillatory propagation of an ionization-shock front

Based on numerical simulations, we show that the oscillatory propagation of a plane-parallel ionization-shock front is possible for a typical dependence of the interstellar-medium cooling function on density and temperature. In this case, the oscillation amplitude of the shock position in the presence of an ionization front can be several times larger than its value for a single shock wave. The variations in neutral and ionized gas velocities attributable to oscillations are comparable in order of magnitude and agree with the random velocities observed in H II regions.     

热电离同位素质谱计负离子检测关键技术的研究

用热电离质谱仪检测负离子，因技术上的原因，一直是国际质谱界关注的热点问题之一。近几年来，在此领域的探索取得突破，发展迅速。新型号的质谱上已大量使用这一技术。国内也填补了这一领域的空白，并将这一技术成功运用于老质谱仪的升级改造。本文重点阐述了作者本人在探索过程中遇到的疑难问题及解决问题的有效方法。